Experimental Investigation of the Performance of Two-Plate Expandable Anchors with Variations in Area and Distance Between Plates in Sandy Soils

Anchors are tensile elements that resist external tensile forces by attaching to structures and being embedded at an optimal depth in the ground. Various types of anchors have been developed for stabilizing both offshore and onshore environments. This study focuses on the experimental examination of a novel type of mechanically expandable plate anchors capable of opening in soil. The impact of various factors including the division of the surface within the plates, pull-out speed, spacing between plates, and soil density on the ultimate pull-out capacity of expandable plate anchors embedded in a sand bed has been explored through physical modeling. To analyze the formation of rupture wedges and the mobilization of the soil volume resting on the plates, particle image velocimetry was employed. Findings indicate that maintaining the plate area constant and altering the area distribution from a scenario of equal-area two-plate anchors to one with greater area allocation on the lower plate enhances the anchor's pull-out capacity by 1.5 times. Furthermore, assessing the functionality of the expandable double-plate anchor across varying pull-out speeds reveals minimal influence of pull-out speed on the pull-out capacity in sandy soils. Among the examined speeds, pulling out the anchors at rates of 10 and 30 mm/min, respectively, in soils of low and high relative densities yielded the highest pull-out forces.